Data Transmission Method, Base Station, And Wireless Communications Device

ABSTRACT

The present invention discloses a data transmission method, a base station, and a wireless communications device, which can ensure normal communication between a terminal and a base station in a multi-stream aggregation scenario. The method includes: receiving, by a primary base station, offloading information sent by a wireless communications device, where the wireless communications device is a secondary base station or a terminal; and adjusting, by the primary base station according to the offloading information, offloading data that is allocated to a multi-stream aggregation base station. The present invention is applicable to the communications field.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/922,940, filed on Oct. 26, 2015, which is a continuation ofInternational Application No. PCT/CN2013/074812, filed on Apr. 26, 2013.All of the afore-mentioned patent applications are hereby incorporatedby reference in their entireties.

TECHNICAL FIELD

The present invention relates to the communications field, and inparticular, to a data transmission method, a base station, and awireless communications device.

BACKGROUND

In a Long Term Evolution (Long Term Evolution, LTE) system, cross-sitecarrier aggregation may exist in the future, that is, multiple differentsites are configured for one terminal, so as to increase a throughput ofthe terminal and simplify terminal mobility management.

In a case of cross-site carrier aggregation, a receive end at a RadioLink Control (Radio Link Control, RLC) layer, a Packet Data ConvergenceProtocol (Packet Data Convergence Protocol, PDCP) layer, or an InternetProtocol (Internet Protocol, IP) layer of an air interface may receivemultiple data streams of one radio bearer (Radio Bearer, RB for short).These data streams come from a multi-stream aggregation (Multiple-streamAggregation, MSA for short) site.

Because load statuses and radio channel conditions of different sitesare different, the multiple data streams of one radio bearer mayexperience different transmission delays, namely, non-uniformtransmission delays. For transmission in an unacknowledged mode(Un-acknowledgement Mode, UM), if multi-stream data is aggregated at theRLC layer, the receive end needs to maintain a reordering window(Reordering Window) to perform, according to a sequence number of theRLC layer, reordering on data delivered from a medium access control(Medium Access Control, MAC) layer, so as to implement sequentialdelivery to the PDCP layer. A size of the reordering window is generallyhalf of a range represented by a sequence number (Sequence Number, SN).For example, if the SN is formed by 10 bits, the size of the reorderingwindow is 512 (that is, half of 2 to the power of 10). How to ensurenormal communication between a terminal and a base station in amulti-stream aggregation scenario has become a problem that needs to beresolved urgently in the industry.

SUMMARY

Embodiments of the present invention provide a data transmission method,a base station, and a wireless communications device, which can ensurenormal communication between a terminal and a base station in amulti-stream aggregation scenario.

To achieve the foregoing objective, the embodiments of the presentinvention provide the following technical solutions:

According to a first aspect, a data transmission method is provided,including:

receiving, by a primary base station, offloading information sent by awireless communications device, where the wireless communications deviceis a secondary base station or a terminal; and

adjusting, by the primary base station according to the offloadinginformation, offloading data that is allocated to a multi-streamaggregation base station; where

when the wireless communications device is the secondary base station,the offloading information includes a sequence number of a packet dataunit PDU sent by the secondary base station to the terminal, and is usedby the primary base station to adjust the offloading data that isallocated to the multi-stream aggregation base station; or when thewireless communications device is the terminal, the offloadinginformation is used by the primary base station to adjust the offloadingdata that is allocated to the multi-stream aggregation base station; and

the multi-stream aggregation base station includes the primary basestation and the secondary base station that participate in multi-streamaggregation.

In a first possible implementation manner, according to the firstaspect, the adjusting, by the primary base station according to theoffloading information, offloading data that is allocated to amulti-stream aggregation base station specifically includes:

determining, by the primary base station according to the offloadinginformation, that a difference between a sequence number of a first PDUthat is waiting to be reordered in a reordering window and an upperboundary of the reordering window is greater than a preset value; and

adjusting, by the primary base station, the offloading data that isallocated to the multi-stream aggregation base station, so that thedifference between the sequence number of the first PDU that is waitingto be reordered and the upper boundary of the reordering window is notgreater than the preset value, where the upper boundary of thereordering window is equal to a value of the largest sequence number ofa PDU received by the terminal plus one, and the preset value is a valuethat is less than or equal to a size of the reordering window.

In a second possible implementation manner, according to the firstpossible implementation manner, when the wireless communications deviceis the secondary base station, the offloading information specificallyincludes a sequence number of a last PDU sent by the secondary basestation to the terminal; and

the determining, by the primary base station according to the offloadinginformation, that a difference between a sequence number of a first PDUthat is waiting to be reordered in a reordering window and an upperboundary of the reordering window is greater than a preset valuespecifically includes:

determining, by the primary base station according to the offloadinginformation, that a maximum difference between sequence numbers of lastPDUs sent separately by the primary base station and by the secondarybase station to the terminal is greater than the preset value.

In a third possible implementation manner, according to the secondpossible implementation manner, before the receiving, by a primary basestation, offloading information sent by a wireless communicationsdevice, the method further includes:

sending a first request message to the secondary base station, where thefirst request message is used to request the secondary base station toreport the sequence number of the last PDU sent to the terminal; or

sending a second request message to the secondary base station, wherethe second request message carries a report period, and is used torequest the secondary base station to report, according to the reportperiod, the sequence number of the last PDU sent to the terminal.

In a fourth possible implementation manner, according to the firstpossible implementation manner, when the wireless communications deviceis the terminal, the offloading information specifically includes:information that the difference between the sequence number of the firstPDU that is waiting to be reordered in the reordering window of theterminal and the upper boundary of the reordering window is greater thanthe preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window.

In a fifth possible implementation manner, according to the fourthpossible implementation manner, receiving, by a primary base station,offloading information sent by a wireless communications device, themethod further includes:

sending a third request message to the terminal, where the third requestmessage is used to request the terminal to send the information that thedifference between the sequence number of the first PDU that is waitingto be reordered in the reordering window of the terminal and the upperboundary of the reordering window is greater than the preset value, orthe sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window; or

sending a fourth request message to the terminal, where the fourthrequest message carries a report period, and is used to request theterminal to report, according to the report period, the information thatthe difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window is greater than the presetvalue, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window.

In a sixth possible implementation manner, with reference to the firstaspect or the first possible implementation manner to the fifth possibleimplementation manner, the offloading information further includes aradio bearer identifier.

According to a second aspect, a data transmission method is provided,including:

sending, by a wireless communications device, offloading information toa primary base station, so that the primary base station adjusts,according to the offloading information, offloading data that isallocated to a multi-stream aggregation base station, where the wirelesscommunications device is a secondary base station or a terminal; and

performing data transmission with the terminal according to theoffloading data that is allocated to the multi-stream aggregation basestation and that is adjusted by the primary base station; where

when the wireless communications device is the secondary base station,the offloading information includes a sequence number of a packet dataunit PDU sent by the secondary base station to the terminal, and is usedby the primary base station to adjust the offloading data that isallocated to the multi-stream aggregation base station; or when thewireless communications device is the terminal, the offloadinginformation is used by the primary base station to adjust the offloadingdata that is allocated to the multi-stream aggregation base station; and

the multi-stream aggregation base station includes the primary basestation and the secondary base station that participate in multi-streamaggregation.

In a first possible implementation manner, according to the secondaspect, when the wireless communications device is the secondary basestation, the offloading information specifically includes a sequencenumber of a last PDU sent by the secondary base station to the terminal.

In a second possible implementation manner, according to the firstpossible implementation manner, before the sending, by a wirelesscommunications device, offloading information to a primary base station,the method further includes:

receiving a first request message sent by the primary base station,where the first request message is used to request the secondary basestation to report the sequence number of the last PDU sent to theterminal;

or,

receiving a second request message sent by the primary base station,where the second request message carries a report period, and is used torequest the secondary base station to report, according to the reportperiod, the sequence number of the last PDU sent to the terminal.

In a third possible implementation manner, according to the secondaspect, when the wireless communications device is the terminal, theoffloading information specifically includes: information that adifference between a sequence number of a first PDU that is waiting tobe reordered in a reordering window of the terminal and an upperboundary of the reordering window is greater than a preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window, where

the upper boundary of the reordering window is equal to a value of thelargest sequence number of a PDU received by the terminal plus one, andthe preset value is a value that is less than or equal to a size of thereordering window; and

before the sending, by a wireless communications device, offloadinginformation to a primary base station, the method further includes:

determining, by the terminal according to a received sequence number ofa PDU, the information that the difference between the sequence numberof the first PDU that is waiting to be reordered in the reorderingwindow of the terminal and the upper boundary of the reordering windowis greater than the preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window.

In a fourth possible implementation manner, according to the thirdpossible implementation manner, before sending, by the terminal, theoffloading information to the primary base station, the method furtherincludes:

receiving a third request message sent by the primary base station,where the third request message is used to request the terminal to sendthe information that the difference between the sequence number of thefirst PDU that is waiting to be reordered in the reordering window ofthe terminal and the upper boundary of the reordering window is greaterthan the preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window;

or,

receiving a fourth request message sent by the primary base station,where the fourth request message carries a report period, and is used torequest the terminal to report, according to the report period, theinformation that the difference between the sequence number of the firstPDU that is waiting to be reordered in the reordering window of theterminal and the upper boundary of the reordering window is greater thanthe preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window.

According to a third aspect, a base station is provided, where the basestation includes a receiving unit and an adjusting unit, where

the receiving unit is configured to receive offloading information sentby a wireless communications device, where the wireless communicationsdevice is a secondary base station or a terminal; and

the adjusting unit is configured to adjust, according to the offloadinginformation, offloading data that is allocated to a multi-streamaggregation base station; where

when the wireless communications device is the secondary base station,the offloading information includes a sequence number of a packet dataunit PDU sent by the secondary base station to the terminal, and is usedby the base station to adjust the offloading data that is allocated tothe multi-stream aggregation base station; or when the wirelesscommunications device is the terminal, the offloading information isused by the base station to adjust the offloading data that is allocatedto the multi-stream aggregation base station; and

the multi-stream aggregation base station includes the base station andthe secondary base station that participate in multi-stream aggregation.

In a first possible implementation manner, according to the thirdaspect, the adjusting unit is specifically configured to:

determine, according to the offloading information, that a differencebetween a sequence number of a first PDU that is waiting to be reorderedin a reordering window and an upper boundary of the reordering window isgreater than a preset value; and

adjust the offloading data that is allocated to the multi-streamaggregation base station, so that the difference between the sequencenumber of the first PDU that is waiting to be reordered and the upperboundary of the reordering window is not greater than the preset value,where the upper boundary of the reordering window is equal to a value ofthe largest sequence number of a PDU received by the terminal plus one,and the preset value is a value that is less than or equal to a size ofthe reordering window.

In a second possible implementation manner, according to the firstpossible implementation manner, when the wireless communications deviceis the secondary base station, the offloading information specificallyincludes a sequence number of a last PDU sent by the secondary basestation to the terminal; and

the adjusting unit is specifically configured to:

determine, according to the offloading information, that a maximumdifference between sequence numbers of last PDUs sent separately by thebase station and by the secondary base station to the terminal isgreater than the preset value; and

adjust the offloading data that is allocated to the multi-streamaggregation base station, so that the difference between the sequencenumber of the first PDU that is waiting to be reordered and the upperboundary of the reordering window is not greater than the preset value,where the upper boundary of the reordering window is equal to a value ofthe largest sequence number of a PDU received by the terminal plus one,and the preset value is a value that is less than or equal to a size ofthe reordering window.

In a third possible implementation manner, according to the secondpossible implementation manner, the base station further includes asending unit, where

the sending unit is configured to send a first request message to thesecondary base station, where the first request message is used torequest the secondary base station to report the sequence number of thelast PDU sent to the terminal; or

the sending unit is configured to send a second request message to thesecondary base station, where the second request message carries areport period, and is used to request the secondary base station toreport, according to the report period, the sequence number of the lastPDU sent to the terminal.

In a fourth possible implementation manner, according to the firstpossible implementation manner, when the wireless communications deviceis the terminal, the offloading information specifically includes:information that the difference between the sequence number of the firstPDU that is waiting to be reordered in the reordering window of theterminal and the upper boundary of the reordering window is greater thanthe preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window.

In a fifth possible implementation manner, according to the fourthpossible implementation manner, the base station further includes asending unit, where

the sending unit is configured to send a third request message to theterminal, where the third request message is used to request theterminal to send the information that the difference between thesequence number of the first PDU that is waiting to be reordered in thereordering window of the terminal and the upper boundary of thereordering window is greater than the preset value, or the sequencenumber of the first PDU that is waiting to be reordered in thereordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window; or

send a fourth request message to the terminal, where the fourth requestmessage carries a report period, and is used to request the terminal toreport, according to the report period, the information that thedifference between the sequence number of the first PDU that is waitingto be reordered in the reordering window of the terminal and the upperboundary of the reordering window is greater than the preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window.

In a sixth possible implementation manner, with reference to the thirdaspect or the first possible implementation manner to the fifth possibleimplementation manner, the offloading information further includes aradio bearer identifier.

According to a fourth aspect, a wireless communications device isprovided, including: a sending unit and a communication unit, where

the sending unit is configured to send offloading information to aprimary base station, so that the primary base station adjusts,according to the offloading information, offloading data that isallocated to a multi-stream aggregation base station, where the wirelesscommunications device is a secondary base station or a terminal; and

the communication unit is configured to perform data transmission withthe terminal according to the offloading data that is allocated to themulti-stream aggregation base station and that is adjusted by theprimary base station; where

when the wireless communications device is the secondary base station,the offloading information includes a sequence number of a packet dataunit PDU sent by the secondary base station to the terminal, and is usedby the primary base station to adjust the offloading data that isallocated to the multi-stream aggregation base station; or when thewireless communications device is the terminal, the offloadinginformation is used by the primary base station to adjust the offloadingdata that is allocated to the multi-stream aggregation base station; and

the multi-stream aggregation base station includes the primary basestation and the secondary base station that participate in multi-streamaggregation.

In a first possible implementation manner, according to the fourthaspect, when the wireless communications device is the secondary basestation, the offloading information specifically includes a sequencenumber of a last PDU sent by the secondary base station to the terminal.

In a second possible implementation manner, according to the firstpossible implementation manner, the wireless communications devicefurther includes a receiving unit, where

the receiving unit is configured to receive a first request message sentby the primary base station, where the first request message is used torequest the secondary base station to report the sequence number of thelast PDU sent to the terminal;

or,

the receiving unit is configured to receive a second request messagesent by the primary base station, where the second request messagecarries a report period, and is used to request the secondary basestation to report, according to the report period, the sequence numberof the last PDU sent to the terminal.

In a third possible implementation manner, according to the secondaspect, when the wireless communications device is the terminal, theoffloading information specifically includes: information that adifference between a sequence number of a first PDU that is waiting tobe reordered in a reordering window of the terminal and an upperboundary of the reordering window is greater than a preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window, where

the upper boundary of the reordering window is equal to a value of thelargest sequence number of a PDU received by the terminal plus one, andthe preset value is a value that is less than or equal to a size of thereordering window; and

the wireless communications device further includes a determining unit,where

the determining unit is configured to determine, according to a receivedsequence number of a PDU, information that the difference between thesequence number of the first PDU that is waiting to be reordered in thereordering window of the terminal and the upper boundary of thereordering window is greater than the preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window.

In a fourth possible implementation manner, according to the thirdpossible implementation manner, the wireless communications devicefurther includes a receiving unit, where

the receiving unit is configured to receive a third request message sentby the primary base station, where the third request message is used torequest the terminal to send the information that the difference betweenthe sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window is greater than the preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window;

or,

the receiving unit is configured to receive a fourth request messagesent by the primary base station, where the fourth request messagecarries a report period, and is used to request the terminal to report,according to the report period, the information that the differencebetween the sequence number of the first PDU that is waiting to bereordered in the reordering window of the terminal and the upperboundary of the reordering window is greater than the preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window.

The embodiments of the present invention provide a data transmissionmethod, a base station, and a wireless communications device. The methodincludes: receiving, by a primary base station, offloading informationsent by a wireless communications device, where the wirelesscommunications device is a secondary base station or a terminal; andadjusting, by the primary base station according to the offloadinginformation, offloading data that is allocated to a multi-streamaggregation base station, where: when the wireless communications deviceis the secondary base station, the offloading information includes asequence number of a packet data unit PDU sent by the secondary basestation to the terminal; or when the wireless communications device isthe terminal, the offloading information is used by the primary basestation to adjust the offloading data that is allocated to themulti-stream aggregation base station; and the multi-stream aggregationbase station includes the primary base station and the secondary basestation that participate in multi-stream aggregation. According to thissolution, the primary base station may adjust, according to theoffloading information sent by the wireless communications device, theoffloading data that is allocated to the multi-stream aggregation basestation, so that a sequence number of a PDU received by the terminalfalls within a reordering window, thereby ensuring normal communicationbetween the terminal and the base station in a multi-stream aggregationscenario.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a data transmission scenario accordingto an embodiment of the present invention;

FIG. 2 is a schematic flowchart of a data transmission method accordingto an embodiment of the present invention;

FIG. 3 is a schematic flowchart of another data transmission methodaccording to an embodiment of the present invention;

FIG. 4 is a schematic flowchart of still another data transmissionmethod according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of receiving a PDU by a terminal accordingto an embodiment of the present invention;

FIG. 6 is a schematic interaction diagram of a data transmission methodaccording to an embodiment of the present invention;

FIG. 7 is a schematic interaction diagram of another data transmissionmethod according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of a format of a PDU according to anembodiment of the present invention;

FIG. 9 is a schematic interaction diagram of still another datatransmission method according to an embodiment of the present invention;

FIG. 10 is a schematic structural diagram of a base station according toan embodiment of the present invention;

FIG. 11 is a schematic structural diagram of another base stationaccording to an embodiment of the present invention;

FIG. 12 is a schematic structural diagram of a wireless communicationsdevice according to an embodiment of the present invention;

FIG. 13 is a schematic structural diagram of another wirelesscommunications device according to an embodiment of the presentinvention;

FIG. 14 is a schematic structural diagram of still another wirelesscommunications device according to an embodiment of the presentinvention;

FIG. 15 is a schematic structural diagram of still another base stationaccording to an embodiment of the present invention; and

FIG. 16 is a schematic structural diagram of yet another wirelesscommunications device according to an embodiment of the presentinvention.

DETAILED DESCRIPTION

The following clearly describes the technical solutions in theembodiments of the present invention with reference to the accompanyingdrawings in the embodiments of the present invention. Apparently, thedescribed embodiments are merely some but not all of the embodiments ofthe present invention. All other embodiments obtained by a person ofordinary skill in the art based on the embodiments of the presentinvention without creative efforts shall fall within the protectionscope of the present invention.

As shown in FIG. 1, FIG. 1 is a diagram of an application scenario of adata transmission method according to an embodiment of the presentinvention. A multi-stream aggregation base station includes the primarybase station and the secondary base station that participate inmulti-stream aggregation. For the scenario diagram shown in FIG. 1, themulti-stream aggregation base station includes a primary base station M,a secondary base station N1, and a secondary base station N2 thatparticipate in the multi-stream aggregation. U is a terminal for whichthe multi-stream aggregation base station provides a service.

When the multi-stream aggregation base station sends a packet data unit(Protocol Data Unit, PDU) to the terminal, the primary base stationfirst allocates offloading data to each multi-stream aggregation basestation, and sends the allocated offloading data to each secondary basestation. After receiving the offloading data sent by the primary basestation, each secondary base station sends the received offloading datato the terminal, and the primary base station also sends, to theterminal, offloading data that is allocated to the primary base station.In the multi-stream aggregation base station, a multi-stream aggregationbase station whose sending speed of the offloading data is the lowest orwhose sending speed of the offloading data is less than a firstthreshold is a low-speed stream base station, and a multi-streamaggregation base station whose sending speed of the offloading data isthe highest or whose sending speed of the offloading data is greaterthan or equal to a first threshold is a high-speed stream base station.

It should be noted that each time the terminal receives a PDU sent bythe multi-stream aggregation base station, the terminal needs todetermine an upper boundary and a lower boundary of a reordering windowaccording to a value of a sequence number of the PDU.

The upper boundary of the reordering window is defined as a lastsequence number of sequence numbers of all PDUs received by the terminalplus one. For example, when a sequence number of a last PDU received bythe terminal is 100, an upper boundary of the reordering window is 101.The lower boundary of the reordering window is defined as a differenceobtained by subtracting a size of the reordering window from an upperboundary of the reordering window. For example, when a sequence numberof a last PDU received by the terminal is 575, the upper boundary of thereordering window is 576, and if a size of the reordering window is 512,the lower boundary of the reordering window is 64.

A sequence number of a first PDU that is waiting to be reordered in thereordering window of the terminal is a sequence number of a first PDUthat is not received and that is in the reordering window, where thefirst PDU that is not received is determined by the terminal accordingto a received sequence number of a PDU.

An embodiment of the present invention provides a data transmissionmethod, and the method is executed by a primary base station. As shownin FIG. 2, the method includes the following steps:

201. The primary base station receives offloading information sent by awireless communications device, where the wireless communications deviceis a secondary base station or a terminal.

After the primary base station allocates offloading data to amulti-stream aggregation base station, and sends the allocatedoffloading data to each secondary base station, the multi-streamaggregation base station sends, to the terminal, the offloading datathat is allocated by the primary base station.

When the wireless communications device is the secondary base station,the offloading information includes a sequence number of a packet dataunit PDU sent by the secondary base station to the terminal, and is usedby the primary base station to adjust the offloading data that isallocated to the multi-stream aggregation base station; or when thewireless communications device is the terminal, the offloadinginformation is used by the primary base station to adjust the offloadingdata that is allocated to the multi-stream aggregation base station.

The secondary base station or terminal sends the offloading informationto the primary base station under a particular triggering condition.

For the secondary base station, the triggering condition may be that allthe offloading data that is allocated by the primary base station to thesecondary base station is sent by the secondary base station.

For the terminal, the triggering condition may be information that theterminal determines that a difference between a sequence number of afirst PDU that is waiting to be reordered and an upper boundary of areordering window is greater than the preset value.

When the wireless communications device is the secondary base station,the offloading information includes the sequence number of the packetdata unit PDU sent by the secondary base station to the terminal. Whenthe wireless communications device is the terminal, the offloadinginformation is used by the primary base station to adjust the offloadingdata that is allocated to the multi-stream aggregation base station.

202. The primary base station adjusts, according to the offloadinginformation, offloading data that is allocated to a multi-streamaggregation base station.

In the prior art, because an upper boundary of a reordering windowvaries according to a sequence number of a PDU received by the terminal,data that is between a lower boundary of a reordering window that isdetermined according to a previous PDU received by the terminal and asequence number of a first PDU that is waiting to be reordered in areordering window that is determined according to a current PDU receivedby the terminal is to be discarded because the data is considered toappear repeatedly because of an underlying error, thereby causing a lossand out-of-order delivery of a large amount of data.

To resolve problems of a loss and out-of-order delivery of a largeamount of data that are caused by non-uniform transmission delays, itshould be ensured that a sequence number of a PDU received by theterminal is in a reordering window.

In this embodiment of the present invention, after receiving theoffloading information sent by the wireless communications device, theprimary base station adjusts, according to the offloading information,the offloading data that is allocated to the multi-stream aggregationbase station.

Specifically, the primary base station determines a sending speeding atwhich the multi-stream aggregation base station sends the offloadingdata to the terminal; it is determined that a multi-stream aggregationbase station whose sending speed of the offloading data is the lowest orwhose sending speed of the offloading data is less than a first presetvalue is a low-speed stream base station; and the primary base stationadjusts a third offloading speed of the low-speed stream base station toa fourth offloading speed, where the third offloading speed is anoffloading speed at which the primary base station currently allocatesthe offloading data to the low-speed stream base station, and the fourthoffloading speed is less than the third offloading speed.

Therefore, the offloading data sent by the primary base station to thelow-speed stream base station is reduced, and the offloading databuffered in the low-speed stream base station is reduced, and then adifference between sequence numbers of PDUs of offloading datamulti-stream sent separately by the low-speed stream multi-streamaggregation base station and by the high-speed stream multi-streamaggregation base station to the terminal may become smaller. As aresult, an upper boundary of a reordering window is reduced with achange of a received sequence number of a PDU, a difference between asequence number of a first PDU that is waiting to be reordered and thatis received by the terminal and the upper boundary of the reorderingwindow is reduced, and a probability at which the received PDU falls outof the reordering window is reduced, which can reduce problems of a dataloss and out-of-order delivery of data that are caused by a transmissiondelay, thereby ensuring normal communication between the terminal andthe base station in a multi-stream aggregation scenario.

Optionally, the primary base station determines a sending speeding atwhich the multi-stream aggregation base station sends the offloadingdata to the terminal; it is determined that a multi-stream aggregationbase station whose sending speed of the offloading data is the lowest orwhose sending speed of the offloading data is less than a first presetvalue is a low-speed stream base station; it is determined that amulti-stream aggregation base station whose sending speed of theoffloading data is the highest or whose sending speed of the offloadingdata is greater than or equal to the first preset value is a high-speedstream base station; the primary base station sends, to the low-speedstream base station, an indication message that instructs the low-speedstream base station to suspend sending, to the terminal, offloading datathat is not sent; and the primary base station allocates, to thehigh-speed stream base station, the offloading data that is not sent bythe low-speed stream base station.

Therefore, the offloading data sent by the primary base station to thelow-speed stream base station is reduced, the offloading data bufferedin the low-speed stream base station is reduced, and the offloading datathat is not sent by the low-speed stream base station is reallocated tothe high-speed stream base station, which reduces a problem of a largedifference between sequence numbers of PDUs received by the terminalthat is caused by a problem of different delays of sending theoffloading data by the low-speed stream base station and the high-speedstream base station. As a result, a difference between reorderingwindows is reduced with a change of a last received sequence number of aPDU, a difference between a sequence number of a first PDU that iswaiting to be reordered and that is received by the terminal and areordering window is reduced, and a probability at which the receivedPDU falls out of the reordering window is reduced, which can reduceproblems of a data loss and out-of-order delivery of data that arecaused by a transmission delay, thereby ensuring normal communicationbetween the terminal and the base station in a multi-stream aggregationscenario.

Optionally, the primary base station may adjust a first offloading speedto a second offloading speed, where the first offloading speed is anoffloading speed at which the primary base station currently allocatesoffloading data to the multi-stream aggregation base station, and thesecond offloading speed is less than the first offloading speed.

Specifically, the primary base station reduces an offloading speed atwhich the offloading data is allocated to each multi-stream aggregationbase station to the second offloading speed. When the primary basestation reduces an offloading speed of each multi-stream aggregationbase station, for the low-speed stream multi-stream aggregation basestation, because offloading data that is allocated by the primary basestation is reduced, the low-speed stream multi-stream aggregation basestation may send all offloading data that is not sent in a buffer; andfor the high-speed stream multi-stream aggregation base station, becausethe offloading data that is allocated by the primary base station isreduced, the high-speed stream multi-stream aggregation base station hasno or a small amount of offloading data to be sent to the terminal. As aresult, a difference between reordering windows is reduced with a changeof a last received sequence number of a PDU, a difference between asequence number of a first PDU that is waiting to be reordered and thatis received by the terminal and a reordering window, and a probabilityat which the received PDU falls out of the reordering window is reduced,which can reduce problems of a data loss and out-of-order delivery ofdata that are caused by a transmission delay, thereby ensuring normalcommunication between the terminal and the base station in amulti-stream aggregation scenario.

According to the data transmission method provided in this embodiment ofthe present invention, a primary base station receives offloadinginformation sent by a wireless communications device, where the wirelesscommunications device is a secondary base station or a terminal; and theprimary base station adjusts, according to the offloading information,offloading data that is allocated to a multi-stream aggregation basestation, where: when the wireless communications device is the secondarybase station, the offloading information includes a sequence number of apacket data unit PDU sent by the secondary base station to the terminal;or when the wireless communications device is the terminal, theoffloading information is used by the primary base station to adjust theoffloading data that is allocated to the multi-stream aggregation basestation; and the multi-stream aggregation base station includes theprimary base station and the secondary base station that participate inmulti-stream aggregation. According to this solution, the primary basestation may adjust, according to the offloading information sent by thewireless communications device, the offloading data that is allocated tothe multi-stream aggregation base station, so that a sequence number ofa PDU received by the terminal falls within a reordering window, therebyensuring normal communication between the terminal and the base stationin a multi-stream aggregation scenario.

Still another embodiment of the present invention provides a datatransmission method, and the method is executed by a wirelesscommunications device. As shown in FIG. 3, the method includes thefollowing steps:

301. The wireless communications device sends offloading information toa primary base station, so that the primary base station adjusts,according to the offloading information, offloading data that isallocated to a multi-stream aggregation base station.

The wireless communications device is a secondary base station or aterminal.

After the primary base station allocates the offloading data to themulti-stream aggregation base station, and sends the allocatedoffloading data to each secondary base station, the multi-streamaggregation base station sends, to the terminal, the offloading datathat is allocated by the primary base station.

When the wireless communications device is the secondary base station,the offloading information includes a sequence number of a packet dataunit PDU sent by the secondary base station to the terminal, and is usedby the primary base station to adjust the offloading data that isallocated to the multi-stream aggregation base station; or when thewireless communications device is the terminal, the offloadinginformation is used by the primary base station to adjust the offloadingdata that is allocated to the multi-stream aggregation base station.

The secondary base station sends the offloading information to theprimary base station under a particular triggering condition.

The triggering condition may be that all the offloading data that isallocated by the primary base station to the secondary base station issent by the secondary base station.

The terminal sends the offloading information to the primary basestation under a particular triggering condition.

The triggering condition may be that the terminal determines that adifference between a sequence number of a first PDU that is waiting tobe reordered and an upper boundary of a reordering window is greaterthan a preset value.

After receiving the offloading information sent by the secondary basestation, the primary base station adjusts, according to the offloadinginformation, the offloading data that is allocated to the multi-streamaggregation base station.

302. The wireless communications device performs data transmission witha terminal according to the offloading data that is allocated to themulti-stream aggregation base station and that is adjusted by theprimary base station.

After the primary base station adjusts the offloading data that isallocated to the multi-stream aggregation base station, the wirelesscommunications device performs data transmission with the terminalaccording to offloading data allocated after the primary base stationadjusts the offloading data.

When the wireless communications device is the secondary base station,because the primary base station adjusts, according to the offloadinginformation reported by the secondary base station, the offloading datathat is allocated to the multi-stream aggregation base station,according to this solution, there is no need to change a chip of theterminal, and a change on a related protocol is relatively small.

When the wireless communications device is the terminal, a status of asequence number of a PDU received by the terminal can be accuratelydetermined, and the offloading data that is allocated to themulti-stream aggregation base station can be more accurately adjusted.

According to the data transmission method provided in this embodiment ofthe present invention, a wireless communications device sends offloadinginformation to a primary base station, so that the primary base stationadjusts, according to the offloading information, offloading data thatis allocated to a multi-stream aggregation base station; and thewireless communications device performs data transmission with aterminal according to the offloading data that is allocated to themulti-stream aggregation base station and that is adjusted by theprimary base station. According to this solution, the primary basestation may adjust, according to the offloading information sent by thewireless communications device, the offloading data that is allocated tothe multi-stream aggregation base station, so that a sequence number ofa PDU received by the terminal falls within a reordering window, therebyensuring normal communication between the terminal and the base stationin a multi-stream aggregation scenario.

Still another embodiment of the present invention provides a datatransmission method. As shown in FIG. 4, the method includes thefollowing steps:

401. A primary base station receives offloading information sent by awireless communications device, where the wireless communications deviceis a secondary base station or a terminal.

A multi-stream aggregation base station is classified into a primarybase station and a secondary base station. After the primary basestation allocates offloading data to a multi-stream aggregation basestation and sends the allocated offloading data to each secondary basestation, the multi-stream aggregation base station sends, to theterminal, the offloading data that is allocated by the primary basestation.

When the wireless communications device is the secondary base station,the offloading information includes a sequence number of a packet dataunit PDU sent by the secondary base station to the terminal, and is usedby the primary base station to adjust the offloading data that isallocated to the multi-stream aggregation base station; or when thewireless communications device is the terminal, the offloadinginformation is used by the primary base station to adjust the offloadingdata that is allocated to the multi-stream aggregation base station.

The secondary base station or terminal sends the offloading informationto the primary base station under a particular triggering condition.

For the secondary base station, the triggering condition may be that allthe offloading data that is allocated by the primary base station to thesecondary base station is sent by the secondary base station.

For the terminal, the triggering condition may be that the terminaldetermines that a difference between a sequence number of a first PDUthat is waiting to be reordered and an upper boundary of a reorderingwindow is greater than a preset value.

402. The primary base station determines, according to the offloadinginformation, that a difference between a sequence number of a first PDUthat is waiting to be reordered in a reordering window and an upperboundary of the reordering window is greater than a preset value.

Currently, an SN (Sequence Number) may be formed by 5 bits or 10 bits.The value of the SN is configured by a radio resource control protocol(Radio Resource Control, RRC) and is used to indicate a sequence numberof a corresponding PDU. A different SN size indicates a different sizeof a corresponding reordering window. For example, when the SN is formedby 10 bits, a size of the reordering window is 512; when the SN isformed by 5 bits, a size of the corresponding reordering window is 16.

In a process of determining, by the primary base station, the differencebetween the sequence number of the first PDU that is waiting to bereordered in the reordering window and the upper boundary of thereordering window, the terminal simultaneously receives a PDU sent bythe multi-stream aggregation base station. Therefore, to enable asequence number of a PDU received by the terminal to fall within thereordering window, when the preset value is less than or equal to a sizeof the reordering window and approximate to the size of the reorderingwindow, the primary base station needs to adjust the offloading datathat is allocated to the multi-stream aggregation base station.

Therefore, the preset value is a value that is less than or equal to thesize of reordering window and approximate to the size of the reorderingwindow.

For example, when a size of the reordering window is 512, the presetvalue may be a value such as 500, 501, 490, 480, or 470. A smallerpreset value indicates that the primary base station adjusts earlier theoffloading data that is allocated to the multi-stream aggregation basestation, which indicates a smaller probability at which a sequencenumber of a PDU received by the terminal falls out of the reorderingwindow.

Specifically, when a radio bearer is established, an upper boundary ofthe reordering window is zero; when a sequence number of a PDU receivedby the terminal falls out of the reordering window, the terminalconsiders that the sequence number is new data, and updates the upperboundary of the reordering window to the sequence number of the PDU plusone; or, when a sequence number of a PDU received by the terminal fallswithin the reordering window, the upper boundary of the reorderingwindow is not updated.

After receiving the offloading information sent by the wirelesscommunications device, the primary base station determines, according tothe offloading information, whether the difference between the sequencenumber of the first PDU that is waiting to be reordered in thereordering window and the upper boundary of the reordering window isgreater than the preset value.

When the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window and the upper boundaryof the reordering window is greater than the preset value, the primarybase station determines that the difference between the sequence numberof the first PDU that is waiting to be reordered in the reorderingwindow and the upper boundary of the reordering window is greater thanthe preset value, and step 403 is performed.

When the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window and the upper boundaryof the reordering window is not greater than the preset value, theprimary base station does not process the offloading data that isallocated to the multi-stream aggregation base station.

403. The primary base station adjusts offloading data that is allocatedto a multi-stream aggregation base station, so that the differencebetween the sequence number of the first PDU that is waiting to bereordered and the upper boundary of the reordering window is not greaterthan the preset value.

When the primary base station determines that the difference between thesequence number of the first PDU that is waiting to be reordered and theupper boundary of the reordering window is greater than the presetvalue, the primary base station adjusts the offloading data that isallocated to the multi-stream aggregation base station.

In the prior art, because of different load statuses and radio channelconditions of multi-stream aggregation base stations that participate inmulti-stream aggregation, multiple PDUs of one radio bearer mayexperience different transmission delays, which causes that PDUsreceived at an RLC layer by a terminal are out of order. Therefore, theterminal needs to maintain a reordering window, so that data at the RLClayer is sequentially delivered to a PDCP layer. The reordering windowis re-adjusted according to a value of a last received PDU, and datathat is not received and is between an upper boundary of a reorderingwindow and an upper boundary of an adjusted reordering window isdiscarded. If a received sequence number of a PDU falls out of thereordering window, the terminal considers that the sequence number isnew data, an upper boundary of the reordering window is correspondinglyupdated, and the data is stored in an access buffer to wait for furtherprocessing. If the sequence number of the received PDU falls within thereordering window, it is required to further determine whether the PDUof the sequence number is received repeatedly or already exceeds a timeof waiting to be reordered. If the PDU belongs to the two types of PDUs,the terminal directly deletes the PDU; otherwise, the PDU is a normallyreceived PDU, and the terminal stores the PDU in the buffer to wait forfurther processing.

For example, as shown in FIG. 5, gray represents a PDU that is notreceived, and white represents a received PDU. An example in which asize of a reordering window is 512 is used for description. For example,when a value of an upper boundary of the reordering window that isdetermined according to a last PDU currently received by the terminal is514, a lower boundary of the reordering window is 2. Compared with asignal condition, and the like, of a multi-stream aggregation basestation that sends PDUs whose sequence numbers are 514 to 520, that of amulti-stream aggregation base station that sends a PDU whose sequencenumber is 521 is relatively good. Therefore, transmission delays of thePDUs whose sequence numbers are 514 to 520 are relatively large, and asequence number of a next PDU received by the terminal is 521. When thesequence number of the next PDU received by the terminal is 521, it maybe determined that 521 is not in the reordering window and is greaterthan the upper boundary of the reordering window, and then it isdetermined that an upper boundary of an adjusted reordering window is522, and an lower boundary of the adjusted reordering window is 10; theterminal delivers, to the PDCP layer, a received PDU whose sequencenumber ranges from 2 to 9 and continuously received PDUs whose sequencenumbers range from 10 to 521, and a PDU whose sequence number rangesfrom 2 to 9 and that is not received is considered to encounter a dataloss. For example, PDUs whose sequence numbers are 6, 8, 13, and 40 arenot received, and then the terminal delivers PDUs whose sequence numbersare 2, 3, 4, 5, 7, 9, 10, 11, and 12 to the PDCP layer, where PDUs whosesequence numbers are 6 and 8 are considered to encounter a data loss,and a PDU whose sequence number is 13 is a first PDU that is waiting tobe reordered.

In this embodiment of the present invention, a primary base station maydetermine a value of a sequence number of a first PDU that is notreceived by a terminal and a value of an upper boundary of a reorderingwindow. When the value of the upper boundary of the reordering window ofthe terminal is 514, a value of a lower boundary is 2, PDUs whosesequence number are 2, 3, 4, 5, 7, and 9 are received, and PDUs whosesequence number are 6 and 8 are not received because of a transmissiondelay, and then a sequence number of a first PDU that is waiting to bereordered and that is received by the terminal is 6. It is assumed thatthe preset value is 480. The primary base station may determine that adifference between the sequence number 6 of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary 514 of the reordering window is 508, and 508 is greaterthan the preset value 480. Therefore, the primary base station adjustsoffloading data that is allocated to a multi-stream aggregation basestation, so that a maximum difference between sequence numbers of PDUsthat are sent, to the terminal, separately by the primary base stationand by each secondary base station that send PDUs to the terminal is notgreater than a size of the reordering window. Therefore, a sequencenumber of a next PDU received by the terminal falls within thereordering window. When a difference between the sequence number of thefirst PDU that is waiting to be reordered and the upper boundary of thereordering window is less than or equal to the preset value, the primarybase station stops adjusting the offloading data that is allocated tothe multi-stream aggregation base station, so that the PDUs can besequentially delivered, thereby ensuring normal communication betweenthe terminal and the base station.

When the wireless communications device is a secondary base station, asshown in FIG. 6, the method includes the following steps:

601. The secondary base station sends offloading information to theprimary base station, where the offloading information is a sequencenumber of a last PDU sent by the secondary base station to a terminal.

After sending all offloading data that is allocated by the primary basestation to the secondary base station, the secondary base station maysend the offloading information to the primary base station.

602. The primary base station determines that a maximum differencebetween sequence numbers of last PDUs sent separately by the primarybase station and by the secondary base station to the terminal isgreater than a preset value.

After receiving the offloading information sent by the secondary basestation, the primary base station determines, according to a sequencenumber of a last PDU sent by the primary base station and a sequencenumber of a last PDU sent by another secondary base station except theprimary base station, whether the maximum difference between thesequence numbers of the last PDUs sent by the multi-stream aggregationbase station to the terminal is greater than the preset value.

When the maximum difference between the sequence numbers of the lastPDUs sent separately by the primary base station and by the secondarybase station to the terminal is greater than the preset value, theprimary base station determines that the maximum difference between thesequence numbers of the last PDUs sent separately by the primary basestation and by the secondary base station to the terminal is greaterthan the preset value.

603. The primary base station adjusts offloading data that is allocatedto the multi-stream aggregation base station.

When the primary base station determines that the maximum differencebetween the sequence numbers of the last PDUs sent separately by theprimary base station and by the secondary base station to the terminalis greater than or equal to the preset value, the primary base stationadjusts the offloading data that is allocated to the multi-streamaggregation base station.

For a method for adjusting, by the primary base station, the offloadingdata that is allocated to the multi-stream aggregation base station,reference is made to the description of the foregoing embodiments of thepresent invention, and details are not described again in thisembodiment of the present invention.

For a case shown in FIG. 5, a sequence number of a last PDU sent by asecondary base station N1 is 7, a sequence number of a last PDU sent bya secondary base station N2 is 5, a sequence number of a last PDU sentby a primary base station M is 513, and then a maximum differencebetween sequence numbers of last PDUs sent separately by the primarybase station M and by the secondary base station N1 and the secondarybase station N2 to the terminal is 513−5=508. 508 is greater than thepreset value 480, and therefore the primary base station needs to adjustthe offloading data that is allocated to the multiple aggregation basestation, so that the terminal can first receive a PDU that is notreceived before, that is, PDUs whose sequence numbers are 6, 8, 13, and40. After the terminal receives a PDU whose sequence number is 6, PDUswhose sequence numbers are 2 to 7 may be sequentially delivered; afterthe terminal receives a PDU whose sequence number is 8, PDUs whosesequence numbers are 2 to 12 may be sequentially delivered; and afterthe terminal receives a PDU whose sequence number is 13, PDUs whosesequence numbers are 2 to 39 may be sequentially delivered. Therefore,no data loss is caused. Then a sequence number of a first PDU that iswaiting to be reordered is updated to 40, and when a size of areordering window is 514, a difference between the sequence number ofthe first PDU that is waiting to be reordered and an upper boundary ofthe reordering window is updated to 474, 474 is less than 480, andtherefore the primary base station stops adjusting the offloading datathat is allocated to the multi-stream aggregation base station.According to this solution, a problem of a data loss caused by atransmission delay is resolved, and normal communication between theterminal and the base station is ensured.

Optionally, before receiving the offloading information sent by thesecondary base station, the primary base station may further send afirst request message to the secondary base station.

The first request message is used to request the secondary base stationto report a sequence number of a last PDU sent to the terminal.

After receiving the first request message sent by the primary basestation, the secondary base station sends, to the primary base station,a sequence number of a last PDU that has been sent.

Optionally, before receiving the offloading information sent by thesecondary base station, the primary base station may further send asecond request message to the secondary base station.

The second request message carries a report period, and is used torequest the secondary base station to report, according to the reportperiod, the sequence number of the last PDU sent to the terminal.

After receiving the second request message sent by the primary basestation, the secondary base station may first report, to the primarybase station, a sequence number of a last PDU that has been sent, andthen enable a timer according to the report period. When the timerexpires, the secondary base station reports, to the primary basestation, the sequence number of the last PDU that has been sent.

Certainly, after receiving the second request message sent by theprimary base station, the secondary base station may also first enablethe timer according to the report period. When the timer expires, thesecondary base station reports, to the primary base station, thesequence number of the last PDU that has been sent.

When the wireless communications device is a terminal, as shown in FIG.7, the method includes the following steps:

701. The terminal determines that a difference between a sequence numberof a first PDU that is waiting to be reordered and an upper boundary ofa reordering window is greater than a preset value, or the sequencenumber of the first PDU that is waiting to be reordered in thereordering window of the terminal and the upper boundary of thereordering window, or the difference between the sequence number of thefirst PDU that is waiting to be reordered in the reordering window ofthe terminal and the upper boundary of the reordering window.

Each time the terminal receives a PDU, the terminal needs to determinean upper boundary and a lower boundary of the reordering windowaccording to a value of a sequence number of the PDU.

Specifically, if a received sequence number of a PDU falls out of thereordering window, the terminal considers that the sequence number isnew data, the upper boundary of the reordering window is correspondinglyupdated, and the data is stored in an access buffer to wait for furtherprocessing. If the sequence number of the received PDU falls within thereordering window, it is required to further determine whether the PDUof the sequence number is received repeatedly or already exceeds a timeof waiting to be reordered. If the PDU belongs to the two types of PDUs,the terminal directly deletes the PDU; otherwise, the PDU is a normallyreceived PDU, and the terminal stores the PDU in the buffer to wait forfurther processing.

Then the terminal determines whether the difference between the sequencenumber of the first PDU that is waiting to be reordered in thereordering window and the upper boundary of the reordering window isgreater than the preset value, or the sequence number of the first PDUthat is waiting to be reordered in the reordering window of the terminaland the upper boundary of the reordering window, or the differencebetween the sequence number of the first PDU that is waiting to bereordered in the reordering window of the terminal and the upperboundary of the reordering window.

702. The terminal sends offloading information to the primary basestation.

The offloading information is information that the difference betweenthe sequence number of the first PDU that is waiting to be reordered andthe upper boundary of the reordering window is greater than the presetvalue. The information may be information that the difference betweenthe sequence number of the first PDU that is waiting to be reordered andthe upper boundary of the reordering window is greater than the presetvalue, or that the difference between the sequence number of the firstPDU that is waiting to be reordered and the upper boundary of thereordering window is not greater than the preset value.

Specifically, when the difference between the sequence number of thefirst PDU that is waiting to be reordered and the upper boundary of thereordering window is greater than the preset value, the terminal sendsthe offloading information to the primary base station.

Optionally, the offloading information may further be the sequencenumber of the first PDU that is waiting to be reordered in thereordering window of the terminal and the upper boundary of thereordering window, or the difference between the sequence number of thefirst PDU that is waiting to be reordered in the reordering window ofthe terminal and the upper boundary of the reordering window.

703. The primary base station determines that the difference between thesequence number of the first PDU that is waiting to be reordered and theupper boundary of the reordering window is greater than the presetvalue.

After receiving the offloading information sent by the terminal, theprimary base station determines whether the difference between thesequence number of the first PDU that is waiting to be reordered and theupper boundary of the reordering window is greater than the presetvalue.

Specifically, when the offloading information is the information thatthe difference between the sequence number of the first PDU that iswaiting to be reordered and the upper boundary of the reordering windowis greater than the preset value, the primary base station determinesthat the difference between the sequence number of the first PDU that iswaiting to be reordered and the upper boundary of the reordering windowis greater than the preset value.

When the offloading information is the sequence number of the first PDUthat is waiting to be reordered in the reordering window of the terminaland the upper boundary of the reordering window, or the differencebetween the sequence number of the first PDU that is waiting to bereordered in the reordering window of the terminal and the upperboundary of the reordering window, the primary base station determines,according to the offloading information, that the difference between thesequence number of the first PDU that is waiting to be reordered and theupper boundary of the reordering window is greater than the presetvalue.

704. The primary base station adjusts offloading data that is allocatedto a multi-stream aggregation base station.

When the primary base station determines that the difference between thesequence number of the first PDU that is waiting to be reordered and theupper boundary of the reordering window is greater than the presetvalue, the primary base station adjusts the offloading data that isallocated to the multi-stream aggregation base station.

For a specific method for adjusting, by the primary base station, theoffloading data that is allocated to the multi-stream aggregation basestation, reference is made to the foregoing embodiments of the presentinvention, and details are not described again in this embodiment of thepresent invention.

Optionally, before receiving the offloading information sent by theterminal, the primary base station may further send a third requestmessage to the terminal.

The third request message is used to request the terminal to send theinformation that the difference between the sequence number of the firstPDU that is waiting to be reordered in the reordering window of theterminal and the upper boundary of the reordering window is greater thanthe preset value, or the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window, or the difference between thesequence number of the first PDU that is waiting to be reordered in thereordering window of the terminal and the upper boundary of thereordering window.

After receiving the third request message, the terminal sends, to theprimary base station, the information that the difference between thesequence number of the first PDU that is waiting to be reordered in thereordering window of the terminal and the upper boundary of thereordering window is greater than the preset value, or the sequencenumber of the first PDU that is waiting to be reordered and the upperboundary of the reordering window, or the difference between thesequence number of the first PDU that is waiting to be reordered and theupper boundary of the reordering window.

Optionally, before receiving the offloading information sent by theterminal, the primary base station may further send a fourth requestmessage to the terminal.

The fourth request message carries a report period, and is used torequest the terminal to report, according to the report period, theinformation that the difference between the sequence number of the firstPDU that is waiting to be reordered in the reordering window of theterminal and the upper boundary of the reordering window is greater thanthe preset value, or the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window, or the difference between thesequence number of the first PDU that is waiting to be reordered in thereordering window of the terminal and the upper boundary of thereordering window.

After receiving the fourth request message, the terminal may firstreport, to the primary base station, the sequence number of the firstPDU that is waiting to be reordered and the upper boundary of thereordering window, and then enable a timer according to the reportperiod. When the timer expires, the terminal reports, to the primarybase station, the information that the difference between the sequencenumber of the first PDU that is waiting to be reordered in thereordering window of the terminal and the upper boundary of thereordering window is greater than the preset value, or the sequencenumber of the first PDU that is waiting to be reordered in thereordering window of the terminal and the upper boundary of thereordering window, or the difference between the sequence number of thefirst PDU that is waiting to be reordered in the reordering window ofthe terminal and the upper boundary of the reordering window.

Certainly, after receiving the fourth request message, the terminal mayalso first enable the timer according to the report period. When thetimer expires, the terminal sends, to the primary base station, theinformation that the difference between the sequence number of the firstPDU that is waiting to be reordered in the reordering window of theterminal and the upper boundary of the reordering window is greater thanthe preset value, or the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window, or the difference between thesequence number of the first PDU that is waiting to be reordered in thereordering window of the terminal and the upper boundary of thereordering window.

If the offloading data that is allocated by the primary base station tothe multi-stream aggregation base station belongs to data of a sameservice, the offloading data does not need to carry a radio beareridentifier. If the offloading data that is allocated by the primary basestation to the multi-stream aggregation base station are multiple typesof service data, the offloading data further needs to carry the radiobearer identifier. Then the offloading information sent by the wirelesscommunications device to the primary base station further includes theradio bearer identifier.

In the prior art, because of different load statuses and wirelesschannel conditions, when a multi-stream aggregation base station sends,to a terminal, offloading data that is allocated by a primary basestation, different delays are generated. In addition, because a size ofa reordering window in an unacknowledged mode is 16 or 512, and thereordering window is relatively small, a sequence number of a PDUreceived by the terminal easily falls out of the reordering windowbecause of a delay, which causes problems of a data loss andout-of-order delivery of data. Therefore, increasing a size of thereordering window may reduce problems of a data loss and out-of-orderdelivery of data that are caused by a transmission delay.

An RLC unacknowledged mode supports segmentation, reassembly, andconcatenation, and a data unit that is sent and received is a PDU. Aformat of the PDU includes two parts: an RLC header structure and data,where the header structure is divided into a fixed part and anextensible part. The fixed part exists in each PDU header, and theextensible part exists only when the extensible part is needed. Thefixed part includes an SN part, an FI part, and an E part and is used toindicate PDU information, and the extensible part includes an LI partand an E part and is used to indicate an included SDU or a length of anSDU segment. According to different services carried in anunacknowledged mode, formats of a PDU are different.

For a format of the PDU shown in FIG. 8, a header of the PDU has threebits that are not used, that is, three Rs; L represents a data part.Therefore, a part or all of these bits may be used to extend an SNrange.

As shown in FIG. 9, the method includes the following steps:

901. A primary base station determines an SN range in which a PDU isnumbered.

When determining to use a bit that is not used to number a PDU, theprimary base station determines an extended SN range. The primary basestation further determines, according to a determined number of bitsthat are not used, the SN range in which a PDU is numbered.

The primary base station may use one, two, or three bits that are notused to determine the SN range in which a PDU is numbered.

Specifically, in the prior art, an SN range determined according to abit of an SN is a first SN range. Therefore, when the primary basestation uses one bit that is not used, the SN range is twice the firstSN range; when the primary base station uses two bits that are not used,the SN range is four times the first SN range; when the primary basestation uses three bits that are not used, the SN range is eight timesthe first SN range.

For example, in the prior art, an SN is formed by 10 bits. When theprimary base station uses one bit that is not used, an SN range isextended from 0-1023 to 0-2047. Because a size of a reordering window ishalf the value of an SN, the size of the reordering window is extendedfrom 512 to 1024.

902. The primary base station sends, to a terminal and a secondary basestation in a multi-stream aggregation base station, a configurationmessage of allocated offloading data, where the configuration message ofthe offloading data carries an extended SN range.

The primary base station may send the configuration message of theoffloading data to the secondary base station by using RRC signaling.

903. The primary base station and the secondary base station send a PDUto the terminal according to the extended SN.

When the terminal performs PDU reordering by using an extendedreordering window, and sequentially delivers the reordered PDUs to aPDCP layer. By using the extended reordering window, when the terminalreceives a PDU sent by the multiple-aggregation base station, because asize of the reordering window is extended, delayed data can fall intothe reordering window, thereby reducing problems of a data loss andout-of-order delivery of data that are caused by a delay.

The foregoing method is described for an RLC layer, for a PDCP layer oran IP layer, a method for implementing, by using a reordering window,sequential delivery of data to an upper layer may be the same as that ofthe RLC layer, and details are not described again in this embodiment ofthe present invention.

According to the data transmission method provided in this embodiment ofthe present invention, a primary base station receives offloadinginformation sent by a wireless communications device, where the wirelesscommunications device is a secondary base station or a terminal; and theprimary base station adjusts, according to the offloading information,offloading data that is allocated to a multi-stream aggregation basestation, where: when the wireless communications device is the secondarybase station, the offloading information includes a sequence number of apacket data unit PDU sent by the secondary base station to the terminal;or when the wireless communications device is the terminal, theoffloading information is used by the primary base station to adjust theoffloading data that is allocated to the multi-stream aggregation basestation; and the multi-stream aggregation base station includes theprimary base station and the secondary base station that participate inmulti-stream aggregation. According to this solution, the primary basestation may adjust, according to the offloading information sent by thewireless communications device, the offloading data that is allocated tothe multi-stream aggregation base station, so that a sequence number ofa PDU received by the terminal falls within a reordering window, therebyensuring normal communication between the terminal and the base stationin a multi-stream aggregation scenario.

Still another embodiment of the present invention provides a basestation. As shown in FIG. 10, the base station 100 includes a receivingunit 101 and an adjusting unit 102, where

the receiving unit 101 is configured to receive offloading informationsent by a wireless communications device, where the wirelesscommunications device is a secondary base station or a terminal; and

the adjusting unit 102 is configured to adjust, according to theoffloading information, offloading data that is allocated to amulti-stream aggregation base station; where

when the wireless communications device is the secondary base station,the offloading information includes a sequence number of a packet dataunit PDU sent by the secondary base station to the terminal, and is usedby the base station to adjust the offloading data that is allocated tothe multi-stream aggregation base station; or when the wirelesscommunications device is the terminal, the offloading information isused by the base station to adjust the offloading data that is allocatedto the multi-stream aggregation base station; and

the multi-stream aggregation base station includes the base station andthe secondary base station that participate in multi-stream aggregation.

Further, the adjusting unit 102 is specifically configured to:

determine, according to the offloading information, that a differencebetween a sequence number of a first PDU that is waiting to be reorderedin a reordering window and an upper boundary of the reordering window isgreater than a preset value; and

adjust the offloading data that is allocated to the multi-streamaggregation base station, so that the difference between the sequencenumber of the first PDU that is waiting to be reordered and the upperboundary of the reordering window is not greater than the preset value,where the upper boundary of the reordering window is equal to a value ofthe largest sequence number of a PDU received by the terminal plus one,and the preset value is a value that is less than or equal to a size ofthe reordering window.

Optionally, when the wireless communications device is the secondarybase station, and the offloading information specifically includes asequence number of a last PDU sent by the secondary base station to theterminal, the adjusting unit 102 is specifically configured to:

determine, according to the offloading information, that a maximumdifference between sequence numbers of last PDUs sent separately by thebase station and by the secondary base station to the terminal isgreater than the preset value; and

adjust the offloading data that is allocated to the multi-streamaggregation base station, so that the difference between the sequencenumber of the first PDU that is waiting to be reordered and the upperboundary of the reordering window is not greater than the preset value,where the upper boundary of the reordering window is equal to a value ofthe largest sequence number of a PDU received by the terminal plus one,and the preset value is a value that is less than or equal to a size ofthe reordering window.

Further, as shown in FIG. 11, the base station further includes asending unit 103, where the sending unit 103 is configured to send afirst request message to the secondary base station, where the firstrequest message is used to request the secondary base station to reportthe sequence number of the last PDU sent to the terminal; or

the sending unit 103 is configured to send a second request message tothe secondary base station, where the second request message carries areport period, and is used to request the secondary base station toreport, according to the report period, the sequence number of the lastPDU sent to the terminal.

Optionally, when the wireless communications device is the terminal, theoffloading information specifically includes: information that thedifference between the sequence number of the first PDU that is waitingto be reordered in the reordering window of the terminal and the upperboundary of the reordering window is greater than the preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window.

Further, the base station further includes a sending unit 103, where

the sending unit 103 is configured to send a third request message tothe terminal, where the third request message is used to request theterminal to send the information that the difference between thesequence number of the first PDU that is waiting to be reordered in thereordering window of the terminal and the upper boundary of thereordering window is greater than the preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window; or

the sending unit 103 is configured to send a fourth request message tothe terminal, where the fourth request message carries a report period,and is used to request the terminal to report, according to the reportperiod, the information that the difference between the sequence numberof the first PDU that is waiting to be reordered in the reorderingwindow of the terminal and the upper boundary of the reordering windowis greater than the preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window.

The adjusting unit 102 is specifically configured to:

adjust a first offloading speed to a second offloading speed, where thefirst offloading speed is an offloading speed at which the base stationcurrently allocates offloading data to the multi-stream aggregation basestation, and the second offloading speed is less than the firstoffloading speed;

or,

determine a sending speed at which the multi-stream aggregation basestation sends offloading data to the terminal;

determine a multi-stream aggregation base station whose sending speed ofthe offloading data is the lowest or whose sending speed of theoffloading data is less than a first preset value as a low-speed streambase station; and

adjust a third offloading speed of the low-speed stream base station toa fourth offloading speed, where the third offloading speed is anoffloading speed at which the base station currently allocatesoffloading data to the low-speed stream base station, and the fourthoffloading speed is less than the third offloading speed;

or,

determine a sending speed at which the multi-stream aggregation basestation sends offloading data to the terminal;

determine a multi-stream aggregation base station whose sending speed ofthe offloading data is the lowest or whose sending speed of theoffloading data is less than a first preset value as a low-speed streambase station;

determine a multi-stream aggregation base station whose sending speed ofthe offloading data is the highest or whose sending speed of theoffloading data is greater than or equal to the first preset value as ahigh-speed stream base station;

send, to the low-speed stream base station, an indication message thatinstructs the low-speed stream base station to suspend sending, to theterminal, offloading data that is not sent; and

allocate, to the high-speed stream base station, the offloading datathat is not sent by the low-speed stream base station.

Optionally, the offloading information further includes a radio beareridentifier.

According to the base station provided in this embodiment of the presentinvention, the receiving unit receives offloading information sent by awireless communications device, where the wireless communications deviceis a secondary base station or a terminal; and the adjusting unitadjusts, according to the offloading information, offloading data thatis allocated to a multi-stream aggregation base station, where: when thewireless communications device is the secondary base station, theoffloading information includes a sequence number of a packet data unitPDU sent by the secondary base station to the terminal; or when thewireless communications device is the terminal, the offloadinginformation is used by the base station to adjust the offloading datathat is allocated to the multi-stream aggregation base station; and themulti-stream aggregation base station includes the base station and thesecondary base station that participate in multi-stream aggregation.According to this solution, the base station may adjust, according tothe offloading information sent by the wireless communications device,the offloading data that is allocated to the multi-stream aggregationbase station, so that a sequence number of a PDU received by theterminal falls within a reordering window, thereby ensuring normalcommunication between the terminal and the base station in amulti-stream aggregation scenario.

Still another embodiment of the present invention provides a wirelesscommunications device. As shown in FIG. 12, the wireless communicationsdevice 120 includes a sending unit 121 and a communication unit 122,where

the sending unit 121 is configured to send offloading information to aprimary base station, so that the primary base station adjusts,according to the offloading information, offloading data that isallocated to a multi-stream aggregation base station, where the wirelesscommunications device is a secondary base station or a terminal; and

the communication unit 122 is configured to perform data transmissionwith the terminal according to the offloading data that is allocated tothe multi-stream aggregation base station and that is adjusted by theprimary base station; where

when the wireless communications device is the secondary base station,the offloading information includes a sequence number of a packet dataunit PDU sent by the secondary base station to the terminal, and is usedby the primary base station to adjust the offloading data that isallocated to the multi-stream aggregation base station; or when thewireless communications device is the terminal, the offloadinginformation is used by the primary base station to adjust the offloadingdata that is allocated to the multi-stream aggregation base station; and

the multi-stream aggregation base station includes the primary basestation and the secondary base station that participate in multi-streamaggregation.

Optionally, when the wireless communications device is the secondarybase station, the offloading information specifically includes asequence number of a last PDU sent by the secondary base station to theterminal.

Further, as shown in FIG. 13, the wireless communications device furtherincludes a receiving unit 123, where

the receiving unit 123 is configured to receive a first request messagesent by the primary base station, where the first request message isused to request the secondary base station to report the sequence numberof the last PDU sent to the terminal;

or,

the receiving unit 123 is configured to receive a second request messagesent by the primary base station, where the second request messagecarries a report period, and is used to request the secondary basestation to report, according to the report period, the sequence numberof the last PDU sent to the terminal.

Optionally, when the wireless communications device is the terminal, theoffloading information specifically includes: information that adifference between a sequence number of a first PDU that is waiting tobe reordered in a reordering window of the terminal and an upperboundary of the reordering window is greater than a preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window, where

the upper boundary of the reordering window is equal to a value of thelargest sequence number of a PDU received by the terminal plus one, andthe preset value is a value that is less than or equal to a size of thereordering window.

As shown in FIG. 14, the wireless communications device further includesa determining unit 124, where

the determining unit 124 is configured to determine, according to areceived sequence number of a PDU, the information that the differencebetween the sequence number of the first PDU that is waiting to bereordered in the reordering window of the terminal and the upperboundary of the reordering window is greater than the preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window.

Further, the wireless communications device further includes a receivingunit 123, where the receiving unit 123 is configured to receive a thirdrequest message sent by the primary base station, where the thirdrequest message is used to request the terminal to send the informationthat the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window is greater than the presetvalue, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window;

or,

the receiving unit 123 is configured to receive a fourth request messagesent by the primary base station, where the fourth request messagecarries a report period, and is used to request the terminal to report,according to the report period, the information that the differencebetween the sequence number of the first PDU that is waiting to bereordered in the reordering window of the terminal and the upperboundary of the reordering window is greater than the preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window.

According to the wireless communications device provided in thisembodiment of the present invention, the sending unit sends offloadinginformation to a primary base station, so that the primary base stationadjusts, according to the offloading information, offloading data thatis allocated to a multi-stream aggregation base station; and thecommunication unit performs data transmission with a terminal accordingto the offloading data that is allocated to the multi-stream aggregationbase station and that is adjusted by the primary base station; where:when the wireless communications device is the secondary base station,the offloading information includes a sequence number of a packet dataunit PDU sent by the secondary base station to the terminal, and is usedby the primary base station to adjust the offloading data that isallocated to the multi-stream aggregation base station; or when thewireless communications device is the terminal, the offloadinginformation is used by the primary base station to adjust the offloadingdata that is allocated to the multi-stream aggregation base station.According to this solution, the primary base station may adjust,according to the offloading information sent by the wirelesscommunications device, the offloading data that is allocated to themulti-stream aggregation base station, so that a sequence number of aPDU received by the terminal falls within a reordering window, therebyensuring normal communication between the terminal and the base stationin a multi-stream aggregation scenario.

Still another embodiment of the present invention provides a basestation. As shown in FIG. 15, the base station 140 includes atransceiver 141 and a processor 142, where

the transceiver 141 is configured to receive offloading information sentby a wireless communications device, where the wireless communicationsdevice is a secondary base station or a terminal; and

the processor 142 is configured to adjust, according to the offloadinginformation, offloading data that is allocated to a multi-streamaggregation base station; where

when the wireless communications device is the secondary base station,the offloading information includes a sequence number of a packet dataunit PDU sent by the secondary base station to the terminal, and is usedby the base station to adjust the offloading data that is allocated tothe multi-stream aggregation base station; or when the wirelesscommunications device is the terminal, the offloading information isused by the base station to adjust the offloading data that is allocatedto the multi-stream aggregation base station; and

The multi-stream aggregation base station includes the base station andthe secondary base station that participate in multi-stream aggregation.

Further, the processor 142 is specifically configured to:

determine, according to the offloading information, that a differencebetween a sequence number of a first PDU that is waiting to be reorderedin a reordering window and an upper boundary of the reordering window isgreater than a preset value; and

adjust the offloading data that is allocated to the multi-streamaggregation base station, so that the difference between the sequencenumber of the first PDU that is waiting to be reordered and the upperboundary of the reordering window is not greater than the preset value,where the upper boundary of the reordering window is equal to a value ofthe largest sequence number of a PDU received by the terminal plus one,and the preset value is a value that is less than or equal to a size ofthe reordering window.

Optionally, when the wireless communications device is the secondarybase station, and the offloading information specifically includes asequence number of a last PDU sent by the secondary base station to theterminal, the processor 142 is specifically configured to:

determine, according to the offloading information, that a maximumdifference between sequence numbers of last PDUs sent separately by thebase station and by the secondary base station to the terminal isgreater than the preset value; and

adjust the offloading data that is allocated to the multi-streamaggregation base station, so that the difference between the sequencenumber of the first PDU that is waiting to be reordered and the upperboundary of the reordering window is not greater than the preset value,where the upper boundary of the reordering window is equal to a value ofthe largest sequence number of a PDU received by the terminal plus one,and the preset value is a value that is less than or equal to a size ofthe reordering window.

Further, as shown in FIG. 15, the base station further includes atransceiver 141, where the transceiver 141 is configured to send a firstrequest message to the secondary base station, where the first requestmessage is used to request the secondary base station to report thesequence number of the last PDU sent to the terminal; or

the transceiver 141 is configured to send a second request message tothe secondary base station, where the second request message carries areport period, and is used to request the secondary base station toreport, according to the report period, the sequence number of the lastPDU sent to the terminal.

Optionally, when the wireless communications device is the terminal, theoffloading information specifically includes: information that thedifference between the sequence number of the first PDU that is waitingto be reordered in the reordering window of the terminal and the upperboundary of the reordering window is greater than the preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window.

Further, the transceiver 141 is configured to send a third requestmessage to the terminal, where the third request message is used torequest the terminal to send the information that the difference betweenthe sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window is greater than the preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window; or

the transceiver 141 is configured to send a fourth request message tothe terminal, where the fourth request message carries a report period,and is used to request the terminal to report, according to the reportperiod, the information that the difference between the sequence numberof the first PDU that is waiting to be reordered in the reorderingwindow of the terminal and the upper boundary of the reordering windowis greater than the preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window.

The processor 142 is specifically configured to:

adjust a first offloading speed to a second offloading speed, where thefirst offloading speed is an offloading speed at which the base stationcurrently allocates offloading data to the multi-stream aggregation basestation, and the second offloading speed is less than the firstoffloading speed;

or,

determine a sending speed at which the multi-stream aggregation basestation sends offloading data to the terminal;

determine a multi-stream aggregation base station whose sending speed ofthe offloading data is the lowest or whose sending speed of theoffloading data is less than a first preset value as a low-speed streambase station; and

adjust a third offloading speed of the low-speed stream base station toa fourth offloading speed, where the third offloading speed is anoffloading speed at which the base station currently allocatesoffloading data to the low-speed stream base station, and the fourthoffloading speed is less than the third offloading speed;

or,

determine a sending speed at which the multi-stream aggregation basestation sends offloading data to the terminal;

determine a multi-stream aggregation base station whose sending speed ofthe offloading data is the lowest or whose sending speed of theoffloading data is less than a first preset value as a low-speed streambase station;

determine a multi-stream aggregation base station whose sending speed ofthe offloading data is the highest or whose sending speed of theoffloading data is greater than or equal to the first preset value as ahigh-speed stream base station;

send, to the low-speed stream base station, an indication message thatinstructs the low-speed stream base station to suspend sending, to theterminal, offloading data that is not sent; and

allocate, to the high-speed stream base station, the offloading datathat is not sent by the low-speed stream base station.

Optionally, the offloading information further includes a radio beareridentifier.

According to the base station provided in this embodiment of the presentinvention, the transceiver receives offloading information sent by awireless communications device, where the wireless communications deviceis a secondary base station or a terminal; and the processor adjusts,according to the offloading information, offloading data that isallocated to a multi-stream aggregation base station, where: when thewireless communications device is the secondary base station, theoffloading information includes a sequence number of a packet data unitPDU sent by the secondary base station to the terminal, and is used bythe base station to adjust the offloading data that is allocated to themulti-stream aggregation base station; or when the wirelesscommunications device is the terminal, the offloading information isused by the base station to adjust the offloading data that is allocatedto the multi-stream aggregation base station. According to thissolution, the base station may adjust, according to the offloadinginformation sent by the wireless communications device, the offloadingdata that is allocated to the multi-stream aggregation base station, sothat a sequence number of a PDU received by the terminal falls within areordering window, thereby ensuring normal communication between theterminal and the base station in a multi-stream aggregation scenario.

Still another embodiment of the present invention provides a wirelesscommunications device. As shown in FIG. 16, the wireless communicationsdevice 150 includes a transceiver 151 and a processor 152, where

the transceiver 151 is configured to send offloading information to aprimary base station, so that the primary base station adjusts,according to the offloading information, offloading data that isallocated to a multi-stream aggregation base station, where the wirelesscommunications device is a secondary base station or a terminal; and

the processor 152 is configured to perform data transmission with theterminal according to the offloading data that is allocated to themulti-stream aggregation base station and that is adjusted by theprimary base station; where

when the wireless communications device is the secondary base station,the offloading information includes a sequence number of a packet dataunit PDU sent by the secondary base station to the terminal, and is usedby the primary base station to adjust the offloading data that isallocated to the multi-stream aggregation base station; or when thewireless communications device is the terminal, the offloadinginformation is used by the primary base station to adjust the offloadingdata that is allocated to the multi-stream aggregation base station; and

the multi-stream aggregation base station includes the primary basestation and the secondary base station that participate in multi-streamaggregation.

Optionally, when the wireless communications device is the secondarybase station, the offloading information specifically includes asequence number of a last PDU sent by the secondary base station to theterminal.

The transceiver 151 is further configured to receive a first requestmessage sent by the primary base station, where the first requestmessage is used to request the secondary base station to report thesequence number of the last PDU sent to the terminal;

or,

the transceiver 151 is further configured to receive a second requestmessage sent by the primary base station, where the second requestmessage carries a report period, and is used to request the secondarybase station to report, according to the report period, the sequencenumber of the last PDU sent to the terminal.

Optionally, when the wireless communications device is the terminal, theoffloading information specifically includes: information that adifference between a sequence number of a first PDU that is waiting tobe reordered in a reordering window of the terminal and an upperboundary of the reordering window is greater than a preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window, where

the upper boundary of the reordering window is equal to a value of thelargest sequence number of a PDU received by the terminal plus one, andthe preset value is a value that is less than or equal to a size of thereordering window.

The processor 152 is further configured to determine, according to areceived sequence number of a PDU, the information that the differencebetween the sequence number of the first PDU that is waiting to bereordered in the reordering window of the terminal and the upperboundary of the reordering window is greater than the preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window.

Further, the transceiver 151 is further configured to receive a thirdrequest message sent by the primary base station, where the thirdrequest message is used to request the terminal to send the informationthat the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window is greater than the presetvalue, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window;

or,

the transceiver 151 is further configured to receive a fourth requestmessage sent by the primary base station, where the fourth requestmessage carries a report period, and is used to request the terminal toreport, according to the report period, the information that thedifference between the sequence number of the first PDU that is waitingto be reordered in the reordering window of the terminal and the upperboundary of the reordering window is greater than the preset value, or

the sequence number of the first PDU that is waiting to be reordered inthe reordering window of the terminal and the upper boundary of thereordering window, or

the difference between the sequence number of the first PDU that iswaiting to be reordered in the reordering window of the terminal and theupper boundary of the reordering window.

According to the wireless communications device provided in thisembodiment of the present invention, the transceiver sends offloadinginformation to a primary base station, so that the primary base stationadjusts, according to the offloading information, offloading data thatis allocated to a multi-stream aggregation base station; and theprocessor performs data transmission with a terminal according to theoffloading data that is allocated to the multi-stream aggregation basestation and that is adjusted by the primary base station; where: whenthe wireless communications device is the secondary base station, theoffloading information includes a sequence number of a packet data unitPDU sent by the secondary base station to the terminal, and is used bythe primary base station to adjust the offloading data that is allocatedto the multi-stream aggregation base station; or when the wirelesscommunications device is the terminal, the offloading information isused by the primary base station to adjust the offloading data that isallocated to the multi-stream aggregation base station. According tothis solution, the primary base station may adjust, according to theoffloading information sent by the wireless communications device, theoffloading data that is allocated to the multi-stream aggregation basestation, so that a sequence number of a PDU received by the terminalfalls within a reordering window, thereby ensuring normal communicationbetween the terminal and the base station in a multi-stream aggregationscenario.

It should be noted that the described apparatus embodiment is merelyexemplary. The units described as separate parts may or may not bephysically separate, and parts displayed as units may or may not bephysical units, may be located in one position, or may be distributed ona plurality of network units. Some or all of the modules may be selectedaccording to actual requirements to achieve the objectives of thesolutions of the embodiments. In addition, in the accompanying drawingsof the apparatus embodiments provided by the present invention,connection relationships between modules indicate that the modules havecommunication connections with each other, which may be specificallyimplemented as one or more communications buses or signal cables. Aperson of ordinary skill in the art may understand and implement theembodiments of the present invention without creative efforts.

Based on the description of the foregoing implementation manners, aperson skilled in the art may clearly understand that the presentinvention may be implemented by software in addition to necessaryuniversal hardware, or by dedicated hardware, including a dedicatedintegrated circuit, a dedicated CPU, a dedicated memory, a dedicatedcomponent, and the like. Generally, any functions that can be performedby a computer program can be easily implemented by using correspondinghardware. Moreover, a specific hardware structure used to achieve a samefunction may be of various forms, for example, in a form of an analogcircuit, a digital circuit, a dedicated circuit, or the like. However,as for the present invention, software program implementation is abetter implementation manner in most cases. Based on such anunderstanding, the technical solutions of the present inventionessentially or the part contributing to the prior art may be implementedin a form of a software product. The software product is stored in areadable storage medium, such as a floppy disk, a USB flash drive, aremovable hard disk, a read-only memory (ROM, Read-Only Memory), arandom access memory (RAM, Random Access Memory), a magnetic disk, or anoptical disc of a computer, and includes several instructions forinstructing a computer device (which may be a personal computer, aserver, a network device, or the like) to perform the methods describedin the embodiments of the present invention.

The foregoing descriptions are merely specific implementation manners ofthe present invention, but are not intended to limit the protectionscope of the present invention. Any variation or replacement readilyfigured out by a person skilled in the art within the technical scopedisclosed in the present invention shall fall within the protectionscope of the present invention. Therefore, the protection scope of thepresent invention shall be subject to the protection scope of theclaims.

1. A data transmission method in un-acknowledgement mode (UM),comprising: receiving, by a primary base station, offloading informationfrom a secondary base station; adjusting, by the primary base stationaccording to the offloading information, amount of data that isallocated to the secondary base station; and wherein the offloadinginformation comprises a sequence number of a last Packet DataConvergence Protocol (PDCP) packet data unit (PDU) from the secondarybase station to a terminal, and a value of the sequence number comprisesan integer.
 2. The method according to claim 1, further comprising:requesting the secondary base station to report the sequence number ofthe last PDCP PDU sent to the terminal.
 3. The method according to claim1, further comprising: requesting the secondary base station to report,according to a report period, the sequence number of the last PDCP PDUsent to the terminal.
 4. The method according to claim 1, whereinadjusting, by the primary base station according to the offloadinginformation, the amount of data that is allocated to the secondary basestation comprises: determining, by the primary base station according tothe offloading information, that a difference between a sequence numberof a first PDU that is waiting to be reordered in a reordering windowand an upper boundary of the reordering window is greater than a presetvalue; and adjusting, by the primary base station, the amount of datathat is allocated to the secondary base station, wherein the differencebetween the sequence number of the first PDU that is waiting to bereordered and the upper boundary of the reordering window is not greaterthan the preset value.
 5. The method according to claim 4, wherein theupper boundary of the reordering window is equal to a value of a largestsequence number of a PDU received by the terminal plus one, and thepreset value is a value that is less than or equal to a size of thereordering window.
 6. A primary base station, comprising: a receiverconfigured to receive offloading information from a secondary basestation; a non-transitory memory storage comprising instructions; andone or more hardware processors in communication with the non-transitorymemory storage, wherein the one or more hardware processors execute theinstructions to: adjust, according to the offloading information, amountof data that is allocated to the secondary base station inun-acknowledgement mode; and wherein the offloading informationcomprises a sequence number of a last Packet Data Convergence Protocol(PDCP) packet data unit (PDU) from the secondary base station to aterminal, and a value of the sequence number comprises an integer. 7.The primary base station according to claim 6, further comprising: atransmitter configured to request the secondary base station to reportthe sequence number of the last PDCP PDU sent to the terminal.
 8. Theprimary base station according to claim 6, further comprising: atransmitter configured to request the secondary base station to report,according to a report period, the sequence number of the last PDCP PDUsent to the terminal.
 9. The primary base station according to claim 6,wherein the one or more hardware processors execute the instructions to:determine, according to the offloading information, that a differencebetween a sequence number of a first PDU that is waiting to be reorderedin a reordering window and an upper boundary of the reordering window isgreater than a preset value; and adjust the amount of data that isallocated to the secondary base station, wherein the difference betweenthe sequence number of the first PDU that is waiting to be reordered andthe upper boundary of the reordering window is not greater than thepreset value.
 10. The primary base station according to claim 9, whereinthe upper boundary of the reordering window is equal to a value of alargest sequence number of a PDU received by the terminal plus one, andthe preset value is a value that is less than or equal to a size of thereordering window.
 11. A data transmission method in un-acknowledgementmode, comprising: sending, by a secondary base station, offloadinginformation to a primary base station; performing data transmission witha terminal according to amount of data that is allocated to thesecondary base station and that is adjusted by the primary base station;and wherein the offloading information comprises a sequence number of alast Packet Data Convergence Protocol (PDCP) packet data unit (PDU) fromthe secondary base station to the terminal, and a value of the sequencenumber comprises an integer.
 12. The method according to claim 11,wherein adjusting the amount of data by the primary base stationcomprises: determining, according to the offloading information, that adifference between a sequence number of a first PDU that is waiting tobe reordered in a reordering window and an upper boundary of thereordering window is greater than a preset value; and adjusting theamount of data that is allocated to the secondary base station, whereinthe difference between the sequence number of the first PDU that iswaiting to be reordered and the upper boundary of the reordering windowis not greater than the preset value.
 13. The method according to claim11, further comprises: receiving, from the primary base station, arequest to report the sequence number of the last PDCP PDU sent to theterminal; or receiving, from the primary base station, a request toreport, according to a report period, the sequence number of the lastPDCP PDU sent to the terminal.
 14. A secondary base station, comprising:a processor; memory coupled to the processor, the memory comprisinginstructions that, when executed by the processor, cause the secondarybase station to: send offloading information to a primary base station;perform data transmission with a terminal according to amount of datathat is allocated to the secondary base station and that is adjusted bythe primary base station; and wherein the offloading informationcomprises a sequence number of a last packet data unit (PDU) sent by thesecondary base station to the terminal, and a value of the sequencenumber comprises an integer.
 15. The secondary base station according toclaim 14, wherein adjusting the amount of data by the primary basestation comprises: determining, according to the offloading information,that a difference between a sequence number of a first packet data unit(PDU) that is waiting to be reordered in a reordering window and anupper boundary of the reordering window is greater than a preset value;and adjusting the amount of data that is allocated to the secondary basestation, wherein the difference between the sequence number of the firstPDU that is waiting to be reordered and the upper boundary of thereordering window is not greater than the preset value.
 16. Thesecondary base station according to claim 15, further comprisinginstructions that, when executed by the processor, cause the secondarybase station to: report the sequence number of the last PDU sent to theterminal; or report, according to a report period, the sequence numberof the last PDU sent to the terminal.